import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * @author krystal
 * @date 2022/12/2 15:55
 * 博客系统
 */
public class UserDao {
    //根据用户名来查询用户的详情
    public User selectByName(String username){
        Connection connection=null;
        PreparedStatement statement=null;
        ResultSet resultSet=null;
        try {
            //1、和数据库建立连接
            connection=DBUtil.getConnection();
            //2、构造sql
            String sql="select * from user where username=?";
            statement=connection.prepareStatement(sql);
            statement.setString(1,username);
            //3、执行sql
            resultSet=statement.executeQuery();
            //4、遍历结果集合
            if (resultSet.next()){
                User user=new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    //根据用户id来查询用户详情
    public User selectById(int userId){
        Connection connection=null;
        PreparedStatement statement=null;
        ResultSet resultSet=null;
        try {
            //1、和数据库建立连接
            connection=DBUtil.getConnection();
            //2、构造sql
            String sql="select * from user where userId=?";
            statement=connection.prepareStatement(sql);
            statement.setInt(1,userId);
            //3、执行sql
            resultSet=statement.executeQuery();
            //4、遍历结果集合
            if (resultSet.next()){
                User user=new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

}
